Lung Volume and Breathing Quiz

Study Notes

Lung volume, or lung capacity, is the maximum volume of air that can be held in the lungs.
The average male adult lung volume is 6 liters, while the average female's is 5.2-4 liters (10-12% smaller).
Lung volume is influenced by height and gender, affecting the size of the thoracic cavity and lungs.
During quiet breathing, only about 0.5 liters of air are inhaled and exhaled.

A spirometer measures lung capacity.
Different types exist, including wet spirometers, which use a tube connected to an inverted container floating on water. The expelled air displaces water.

A spirograph represents the amount of air moving in and out of the lungs with each breath.
The graph shows the volume of air in the lungs over time.

Tidal volume is the volume of air breathed in and out in one normal breath. Typically around 0.50 L.
Only about 0.35 L of air reaches the alveoli; the rest fills the trachea, bronchi, and bronchioles.
With an average respiratory rate of 12-20 breaths per minute, 4.2-7 L of air is exchanged per minute.
Inspiratory reserve volume is the additional volume of air that can be inhaled beyond a normal breath. It involves expanding the lungs, using neck and abdominal muscles along with the diaphragm and intercostal muscles.
Expiratory reserve volume is the additional volume of air that can be exhaled beyond a normal breath.

Inspiratory capacity is the total amount of air that can be inhaled. This is the sum of tidal volume and inspiratory reserve volume.
Vital capacity is the total volume of gas that can be moved in and out of the lungs. This is the sum of inspiratory capacity + expiratory reserve volume.
Total lung volume is the total amount of gas that can be held in the lungs and is equal to the sum of vital capacity and residual volume.
Residual volume is the amount of gas remaining in the lungs and airways after a forced exhalation. This prevents lung collapse (~1L).

Exercise: Extended exercise increases lung capacity and tidal volume.
Illness: Illness can decrease vital capacity and tidal volume by affecting the number of alveoli or weakening the breathing muscles. Tidal volume and vital capacity are reduced.

A table of patient data, showing tidal volume, vital capacity, and respiratory rates, is included and used to answer questions related to a long-distance runner or someone with a respiratory disorder.
Key differences between tidal volume and vital capacity include that tidal volume describes regular breathing; vital capacity shows maximum air intake/exhale.
Based on the data, patient #5 is likely a long-distance runner, having the largest vital capacity and a lower respiratory rate.
Patient #3 is potentially suffering from a respiratory disorder – they show a lower than average tidal volume with a higher than average respiratory rate.